The invention relates to devices for testing and evaluation of characteristics of information and recognizing systems in particular imaging systems. It may be used with efficiency for testing of medical and industrial diagnostic systems, e.g., estimating their detectability of defects and pathological details. The invention is suitable for X-ray, gamma and ultrasound diagnostic systems as well as for computer tomography and magnetic resonance imaging.
At present many of phantoms for quality control of medical and industry diagnostic systems are known (booklets of RMI, Inc., Nuclear Associates, Inc., PTW-Freiburg, Inc.; Phantoms and Computational Model in Therapy, Diagnostics and Protection--ICRU Report 48 June 1992; Test Phantoms and Optimization in Diagnostic Radiology and Nuclear Medicine--Proceedings of Discussion Workshop held in Wurzburg, Germany 15-17 June, 1992).
Most of these phantoms have definitely disposed test elements simulating defects or pathologies. The diagnostic system is evaluated by distinguishing various test elements on the output image of the system and by defining the minimum detectable size of the test element.
The main shortcoming of known phantom is the fixed position of test elements that is known to the examiner beforehand. The impossibility of impartial testing leads often to conflicting opinions between producers and users of diagnostic equipment. RMI's Low Contrast Resolution Test Tool, Model 151 or Contrast Resolution Tissue-equivalent Ultrasound Test Object (U.S. Pat. No. 4,331,021) can serve as examples of such phantoms. There are also test phantoms with changeable position of test elements (Inventor's certificate of USSR No 699915). However the lack of identification of phantom areas on the output image, which determinate coordinates of each distinguished element does not make it possible to obtain probabilities of true, true-positive and false-positive answers of the examiner. Thus it is also impossible to obtain an impartial quantitative assessment of detectability of phantom details.